1. Field of the Invention
This invention relates generally to radar arches for marine vessels.
2. Background Art
Radar arches are often deployed on marine vessels. In use, such arches not only provide a mount for radar, but also for supporting a number of other devices and accessories. They include, for example, dinghy davits, a flag pole, TV antenna, loran antenna, transom light, wind generator, solar panel, backup VHF antenna, GPS antenna, and attachment points for a sunshade.
Preferably, from a visual viewpoint, the design of a radar arch should complement the lines of the boat, for example, by providing a curvature to the top of the arch and legs which support the arch in order to complement the transom and cabin lines. In some cases, the radar arch is anchored into the stern pulpit for additional stiffness. Conventionally, notably in fiberglass structures, stiffness has been provided by combining the stern pulpit and radar arch into a single rigid structure.
In practice, it may be desirable to have a radar arch that is high enough overhead in order to reduce radiation scatter in the cockpit.
Traditionally, the radar arch typically includes an arch member with a generally inverted U-shaped configuration that includes two side members that are joined by a transverse top portion which spans the vessel laterally. The downwardly extending side members supportably engage a base which may be the gunnel of the boat or its deck, or other superstructure.
Conventional high arches may not be sufficiently rigid and stable laterally. In rough seas, boat-to-wave impacts—especially at higher boat speeds—such arches may tend to result in vibration of the radar arch from side to side—“racking”. The lower ends of the arch connected to the boat remain fixed while the upper portions of the arch are subjected to forces that urge lateral movement. This increases in proportion to height above the mounting surface. In general, the upper transverse portion of the radar arch may experience the greatest amount of movement.
This racking has several adverse consequences. First, the racking movement may be visually apparent. This may be viewed by the maritimer as inferior construction. Additionally, boat equipment mounted on and within the radar arch may suffer from excessive shaking. The radar transmitter mounted atop the radar thus may be most detrimentally affected as a result of the vibration. Moreover, should the racking of the radar arch become excessive and last for a sufficient amount of time, portions of the radar arch may begin to crack and fail.
Among the art considered in preparing this patent application are the following U.S. references: U.S. Pat. Nos. 6,927,743; 5,669,325; 4,951,594; and 4,694,773.